There are two types of text that may be added to video: subtitles and captions. Generally speaking, subtitles are intended for hearing audiences and captions for deaf audiences. Subtitles may translate the dialog into a different language, but rarely show all of the audio. For example, captions show sound effects (e.g., “phone ringing” and “footsteps”), while subtitles don't.
Closed captions are captions that are hidden in a video signal, invisible without a special decoder. The closed captions are hidden, for example, in line 21 of the vertical blanking interval (VBI). Open captions are captions that have been decoded, so they have become an integral part of the television picture, like subtitles in a movie. In other words, open captions cannot be turned off. The term “open captions” is also used to refer to subtitles created with a character generator.
The use of text in two-dimensional (2D) video is known by those skilled in the art. The current interest in three-dimensional (3D) video and film has created the need for techniques to add text to 3D content. Therefore, a need exists for techniques for optimizing the insertion of text into 3D content such that the added text does not obstruct the 3D effects in the 3D content and does not create visual fatigue when the 3D content is viewed.